Rear End Rub/Rub/Rub noise when Turning

[CBJoe]

I hate asking this question...because I know its been covered a lot, but I want to be sure I'm not missing any steps while troubleshooting and narrowing down. When the drivetrain is warmed up (eg. 10 mins of driving) I get a Rub-Rub-Rub vibration/noise from the rear end ONLY when turning (left or right). It feels like its coming from the rear end. When I first start driving (eg. driveline cold) there is no noise....its only after driving for 10mins or so. NO discernable noises when driving straight or sweeping turns.

76 Cherokee w/ Quadra-Trac and stock open diffs (3.54 Ratio)
- Fluid Changed in Front/Rear Diffs and QTrac (correct TC-1 Fluid in Transfer Case)
- QTrac Chain Slack free play checked good

I set up a go-pro underneath while doing figure 8-s....and though I could "hear" and feel it from in the cab, I couldn't pic up on any noises on go-pro footage. No indication of wheel hop. But I figured if it was stuck in e-drive, then it wouldn't matter if cold or warm.

Currently jeep is up on jackstands waiting on new drums and shoes to be delivered. I cant feel any play in the axle bearings. I'm considering going ahead and pulling the axles.

Does this sound like a worn bearing to you all? Or something with the diff or transfer case?

Joe

[aantalis]

I had this exact problem and feared it was a major rear end issue. Called an old timer transmission guy familiar with quadratrac and he said try this additive in the rear diff and drive figure 8s in a parking lot several times. My rear diff (79 Cherokee) had a rubber plug on the rear facing side. I pulled it off, extracted 4oz of fluid with a syringe and tubing, put the 4 oz of Ford Motorcraft Additive Friction Modifier, put plug back on diff and drove figure 8s. After a just a few turns it was better, after 10 the rub was gone. Got the product at Ford dealership for about $8 a bottle but available on Amazon here:

4STEED MOTORS 2PCS OEM Genuine XL3 Friction Modifier LSD Additive Limited Slip Differentials XL-3 https://www.amazon.com/dp/B09HR841TX/re ... UTF8&psc=1

[CBJoe]

But the diff isn’t a limited slip,or at least mine isn’t, so there are no clutch packs needing the modifier.

Was yours a LSD?


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[Stuka]

If you have it up on jack stands already, its four bolts per side to pull the axles and check the bearings. It certainly could be bearings based on the sound. And possible they only start making noise once they heat up.

[aantalis]

So, I’m kind of a newbie on the form. (1979 Cherokee automatic). I assumed that because it is Quadra Trac transmission that the rear differential is open. Perhaps the advice I was given regarding the additive presumed that I had a limited slip differential, however I can only say that the additive worked immediately and has been working since. It’s possible I simply needed a differential fluid change for more lubrication? I’m not sure exactly. Unless I misunderstood that the Dana 44 in a Quadra Trac is not necessarily an open differential.

[CBJoe]

I dont believe jeep ever offered the TackLok or LSD with the QTrac Transfer Case. Mine for sure is an open diff...when off the ground...spin one wheel and the other spins in opposite direction.

I think while I'm pulling the axles to inspect the bearings I'll probably go ahead and open the diff cover to visually inspect. Stupid brake drums aren't available locally anywhere in the Indianapolis area. So Ordered them and wont have till next week sometime.

Joe

[Yeller]

As stated check the wheel bearings. They don’t have to howl to be a problem. I recently had a vibration that would come and go, no leaks, no noise, vibration was worse in turns. Wheel bearings were so bad I don’t know how they didn’t completely fail and let the axle walk out. Also have you tried riding the brakes to see if it changes?

[tgreese]

I dont believe jeep ever offered the TackLok or LSD with the QTrac Transfer Case. Mine for sure is an open diff...when off the ground...spin one wheel and the other spins in opposite direction. ...

This is correct. All the Borg-Warner Quadratrac Jeeps '73-79 got open axles, front and rear. Friction additive will have zero effect on an open differential.

[CBJoe]

The tapered bearing and race seem fine to me. The race is smooth with no ripple or divots. The rollers all feel smooth.

I did notice that I can move the race in/out a bit in the axle tube with my fingers….that seems strange to me…but I haven’t changed these before so don’t know if normal or not.

[CBJoe]

I pulled the diff cover and visually everything looks good. Ring Gear, Pinion and Spider Gears appear visually ok. I suppose I should bust out my dial indicator and check backlash.

However...I am now really questioning the QTrac E-Drive.

I have the transmission in Neutral and the Low Range Unit in Neutral....but Still cannot rotate the driveshaft by hand. With the low range unit in Neutral, if the E-Drive was engaged, would it still have everything locked?

EDIT: I think I need to sit down and read TSM and some QTrac info more….I keep faking myself out because I don’t think I completely understand the QTrac behavior while things are up off ground. With the transfer case in neutral and transmission in park, the front/rear driveshaft turn together. With Transfer Case in Hi and the trans in park, neither driveshaft will turn.

[tgreese]

Low range is a planetary transmission on the transmission output, and Irecall that's your only neutral in the transfer case. With the low range in neutral, the drive shafts will be locked together in e-drive. In full-time mode, they are still held together by the friction in the brake cones between the drive shafts. There is a spec in the TSM for how much torque should be needed to make the driveshafts turn against each other. You can measure this with a suitable torque wrench.

I would not expect much difference in feel between e-drive and full-time, if I tried to turn a driveshaft by hand. Everything out to the wheels is connected, which is a lot of load to turn by hand.

[CBJoe]

I was reading a bit more about the figure 8s that are recommended to free up the stuck cones (stick slip)...over on Jubili Jeeps qtrac page it mentions doing 15 mins of figure 8s....to be honest I only had done like 2 mins of them.

For now, the Axle Bearings look good, the Diff looks good, the U-Joints are free. Once the drums and shoes come in I"m going to lube everything up really well and put it all back together and see how it does. I'll put on some good music and drive figure 8s for 15 mins and see what happens.

I also have to replace the gasket on the access cover for the vacuum switch on transfer case. I'll do some inspection there just because it will all be up and open.

Joe

[CBJoe]

hmmm...I feel like my situation is described in this OLD ifsja thread. http://www.ifsja.org/forums/vb/showthread.php?t=165937

now I'm thinking it really was stick-slip symptoms and I need to do some more figure 8s!

[aantalis]

Joe,
After I put the differential additive in I drove figure eights for about 15 minutes and my problem gradually went away. After reading everything and understanding it better it probably had nothing to do with the additive and a lot to do with doing all the figure eights!

[CBJoe]

Short update. I got the jeep back on the road and did some shake down tests. I took to a parking lot and did some figure 8s for quite a bit, but the rear end noise didn't go away.

I decided to pull the front and rear driveshafts and have them rebuilt with new u-joints and balanced. A couple of the old u-joints had broken grease fittings but nothing was super bad. However the guy at the shop pointed out that my rear driveshaft was out of phase front to rear So the slip yoke at the front of the rear driveshaft was 90deg out of place. We'll see how it behaves when I put it all back together.

Before I install the rear driveshaft I'm going to do a torque bias check on the QTrac to see how it does. May even do a short drive with it locked in e-drive and only the front driveshaft installed. Fingers crossed I can resolve it without too much more $$ investment.

Joe

[Stuka]

Having the drive shafts out of phase can cause a lot of vibrations. Not sure if it would cause the sound you heard. Though a bad u-joint certainly could. With any luck, it will go away with the rebuild drive shafts.

Testing the center diff is a good idea, as is testing with just the front shaft hooked up. If it feels like the trans is slipping with just the front hooked up, it means you arent actually in e-drive.

[CBJoe]

Thanks...will do. Hopefully the E-Drive is functioning. I did use a vacuum pump to test all the lines to and from the switch and actually replaced the glovebox switch with one of those BJs units. The other day I actuated the switch and the e-drive light came on and went off when I switched back (did it while rolling idle).

Driveshafts should be done tomorrow so I'll throw the front on in first and test. Boy...the bolts for the Rear yoke on the front shaft were a PITA. I almost considered dropping the trans support. But I just took my time. Hopefully getting them in will be easier because it will be cleaned and not caked with grease

[SJTD]

With the rear on stands did you feel for in/out play on the wheels? Too much axial play and the outer end moves radially. Any evidence of rubbing on the drum or backing plate?

[CBJoe]

With the rear on stands did you feel for in/out play on the wheels? Too much axial play and the outer end moves radially. Any evidence of rubbing on the drum or backing plate?

No evidence of either that I can remember. There was no change from before and after I pulled axles, inspected and greased wheel bearings and replaced drums/shoes. Same Same

[CBJoe]

Partial Test Results:

Driveshafts all back, rebuilt and balanced. Some u-joints were a bit sloppy, but not to the extreme. Big thing was the rear shaft being out of phase. I installed the front driveshaft and took it for a drive.

As you say Stuka...in E-Drive it drove just fine with only the front driveshaft. There was ZERO noise from the rear end doing tight figure 8s. TBH it drove very well. Out of E-Drive it was as described with transmission slipping feel/noise.

Had a rain squall move in while installing the rear driveshaft. Once it calms down I'm gonna go for a test drive to see if noise is still there.

With all the above info....if YES then its the QTrac Related...if NO....then bam! fixed

Cheers, Joe